1. Field of the Invention
The present invention relates to methods of improving the aesthetic appearance of skin and/or hair. More particularly, the present invention relates to methods of darkening skin and/or hair. The present invention also relates to compositions that may be used for self-tanning or darkening skin or change and/or darken the color or shade of hair.
2. Description of the Prior Art
Despite the known detriments of ultraviolet exposure, such as erythema, sunburn and incident sun damage, consumers still desire to increase the pigmentation of their skin, i.e. xe2x80x9ctanningxe2x80x9d, that occurs when the skin is exposed to ultraviolet radiation. The cosmetic industry has attempted to fill the needs of consumers by providing tanning products that do not require ultraviolet exposure. These products are known as self-tanning products.
Typically, such self-tanning products contain dihydroxyacetone (xe2x80x9cDHAxe2x80x9d). DHA imparts a brown color by binding to proteins on the outer layer of skin. Since the outer layer of skin continually sloughs off, the results are temporary. In addition, tans obtained by DHA often appear unnaturally orange or yellow, as well as uneven or xe2x80x9cstreakyxe2x80x9d. Consumers of self-tanning products would prefer a product that imparts a more natural looking, more aesthetically pleasing tan.
Also, a natural tan, that occurs as a result of exposure to ultraviolet radiation, results in an increase in darkening of the skin. This increase in pigmentation also protects the skin against subsequent exposure to ultraviolet exposure.
Sunless tanning products that rely on dying agents, such as DHA, do not affect the amount or quality of pigments in the skin. Thus, such products do not provide protection against subsequent ultraviolet exposure. Clearly, consumers of self-tanning agents desire a product that will provide the added benefit of protection from the effects of subsequent exposure to ultraviolet radiation.
The prior art discusses increasing pigmentation of skin by the use of melanotropic peptides. However, melanotropic peptides present unwanted side effects.
There are also consumers who desire products that change and/or darken the color or shade of hair.
Thus, there is a desire for a composition that can provide tanning of skin without exposure to the sun. There is also a desire for a composition that when topically applied provides photoprotection from subsequent exposure to ultraviolet radiation, especially from the sun. Further, there is a desire for such a composition that will also change and/or darken the color or shade of hair.
It is an object of the present invention to provide a composition that increases melanin production in the skin and/or hair.
It is another object of the present invention to provide a composition that increases the pigmentation of skin and/or hair.
It is still another object of the present invention to provide a composition having methylthioadenosine in an amount effective to increase the pigmentation of skin and/or hair.
It is a further object of the present invention to provide a method of increasing melanin production in the skin and/or hair without exposure to the sun.
These and other objects and advantages of the present invention are achieved by a composition having methylthioadenosine. Preferably, the methylthioadenosine is present in an effective amount about 0.001 wt % to about 20 wt % of the total weight of the composition.
The present invention also provides a method of increasing melanin production in skin and/or hair. The method includes applying to the skin and/or hair, an effective amount of methylthioadenosine, in a cosmetically and/or pharmaceutically acceptable vehicle.